Process of roasting sulphide ores



ore is not diminished, and may in fact be.

somewhat increased. It is my discovery however that in order toaccomplish the best recovery it is essential that the roasting con-Iditions should be so controlled and regulated that at an intermediatestage of the process, immediately preceding the sulfate-decomposingroast the water-soluble content of the calcine should attainsubstantially the maxilnum proportion.

While the process is chiefly intended Jfor the treatment of sulphideores, it will be understood that mixtures of oxidized and sulphide oresmay be treated with like results, provided the sulfur content of the oreor ore-mixture is sufficient to sulfatize the copper from the oxidizedorc. The sulfur content may of course be readily adjusted by theaddition of iron sulphide or equivalent sulfur bearing materialsWhenever the amount of sulfur normally carried by the ore isinsufticient for the purposes of the invention. l

It will be understood that the present invention is not restricted tothe employment of the precise temperaturesor otherpoperating conditions.described herein;

and asy stated above it is applica-ble to all such metals as yieldWater-soluble sulfates. The term ore is used to include concentrates andsimilar metallurgical products.

I claim:

l. Process of roasting sulphide ores, comprising heating the orc withaccess of air to `a reacting temperature below the ignition point of thesulfur in the ore, maintaining such temperature until the maximumprophrtion of the sulphide of the metal to be ext'acted has been.oxidized to sulfate, and

.thereafter decomposing a portion of the suliatc to establish thedesiredacid-balance in the process.

2. Process of treatiiw terrucinous co er- I sulphide ores, about SOO-850F. until the formation of copper sulfate has reached substantially themaximum; then further heating to l- ()O F. to decompose sulfate of ironWith further sulfatizing ot the copper content ot the ore, and finallyraising the temperature to decompose a portion of the copper sul Jfate,thereby establishing the desired acid balance in the process.

3. In a process ot roasting ores containing a sulphide ot a metalyielding a water-soluble sulfate, the steps comprising subjecting thcore to a sulfatizing roast to ellcct substantially the maximumpracticable conver-v sion of the metal into sulfate, and thereafterdecomposing, at a higher temperature, a suiicient proportion ot thesulfate to establish the desired acid-balance in the process.

In testimony whereof, I affix my signature.

PERCY R. MIDDLETON.

comprising vroasting the ore at'

